Flow Rate
Volume moved per unit time - pumps, pipes, tanks and treatment processes.
Why this matters
Where it occurs
Operators check pump output, plumbers size supply lines, treatment plants track flow through every process stage.
Why calculate it
Flow rate is the heartbeat of any liquid system - everything from pipe sizing to dosing depends on knowing it.
What decision it supports
Is the pump delivering its duty point? Is the pipe sized correctly? How long to fill or empty this tank?
What happens if it is wrong
A unit mix-up (litres vs cubic metres, minutes vs seconds) can mis-size equipment by a factor of 60 or 1000.
The concept
Flow rate is simply volume divided by time: Q = V / t. A pump that moves 600 L in 4 minutes is doing 150 L/min.
In piping, flow rate and cross-sectional area give velocity: v = Q / A. Velocity limits keep erosion and noise under control.
Units are where mistakes live: 1 m³ = 1000 L, and 1 L/s = 60 L/min. Convert before you calculate, and check that the answer makes physical sense.
Formula
Flow Rate
Q = V / t
- Q = Flow rate (L/min, L/s or m³/h)
- V = Volume moved (L or m³)
- t = Time (min or s)
Worked example
Problem: A transfer pump moves 600 L in 4 minutes. What is the flow rate?
- Use Q = V / t.
- Substitute: Q = 600 / 4.
- Calculate: Q = 150 L/min.
150 L/min - compare with the pump's rated duty point to judge its health.
Quick solve: practice it
Convert 150 L/min to cubic metres per second.
Quick-solve habit: calculate, then ask yourself - does this answer make sense in real units?
Games that use this mathematics
Apply the calculation inside a workplace simulation.